Stupid question, sorry. SA vs DA

Discussion in 'General Firearms Discussion' started by bluharley, Sep 25, 2014.

  1. bluharley

    bluharley Member

    Ok, I have to admit I am confused about SA vs DA on semi-automatic guns. Once the chamber is loaded, and you fire, another round is loaded. So when I see a pistol advertised as a "single action model", what the hell are they talking about? I've read articles, and I'm still confused. Can anyone explain it so a monkey can understand it?
  2. planosteve

    planosteve Lifetime Supporter

    Ok single action think 1911. If a round is chambered but the hammer is forward you must manually cock the hammer for it to fire. Double action would be like a Sig 226 if the hammer is forward by pulling the trigger you cock the hammer and then it goes bang.
    Last edited: Sep 25, 2014

  3. lklawson

    lklawson Staff Member

    On a semi-auto handgun, the action of the slide during recoil typically will cock the hammer while it strips a round from the magazine and loads it into the chamber. Because you pull the trigger to merely "release" the hammer (or the striker) it is a "Single Action" trigger press; it only performs one "action." A "Double Action" would mean that it has to both cock and then release the hammer. I.E., the hammer is "down" and not cocked. A trigger press must perform two distinct "actions" (cock the hammer and release the hammer off of the sear).

    Some designs of semi-auto have only single action capability, such as the classic 1911. If the hammer falls on a dud or the hammer fails to be cocked back during recoil for whatever reason, no amount of pulling the trigger will cock the hammer back again; jack the slide or "thumb cock" it. Most semi-auto handguns are capable of both Single Action and Double Action, such as the Beretta M9, but some are capable of Double Action only (aka: DAO), such as the Kel Tec P11.

    Triggers operating in DA typically have a longer travel or pull and are usually harder to pull ("heavier") because of the additional force required to compress the Hammer Spring (or striker spring). Triggers operating in SA typically require much less force to pull ("lighter") and usually have a much shorter "travel" because all that is required is just to release the sear and let the compressed spring push the hammer/striker home.

    Peace favor your sword,
    Last edited: Sep 25, 2014
  4. bluharley

    bluharley Member

    So a semi with a hammer that cocks and releases with a trigger pull is DA, all others are SA. So, same as a revolver. Thanks. Specifying a "single action model" sounds like an irrelevant statement when the pics shows no hammer.
  5. lklawson

    lklawson Staff Member


    Sort of. Except for designs that can be used in either SA or DA, such as most handguns chambered for the 9x18 Makarov. And that's without arguing about the Glock design which used the action of the slide to "partially" compresses the striker spring.

    Except that most SA revolvers won't cock the hammer for you under recoil.

    Striker fired pistols, such as the Hi Point, are this way. Pulling the trigger will never compress the striker spring to "cock" the firearm. It can only release the sear.

    Peace favor your sword,
  6. FlashBang

    FlashBang I Stand With Talon Lifetime Supporter

    And for further confusion.... let's toss in some semi-auto's that are double strike. ;)

  7. bluharley

    bluharley Member

    I think in my price range, like under $300, I'm not going to run into those fancy ones!
  8. You might be surprised.

    Often called DA/SA

    The trigger wil raise the hammer, and release it. (DA)
    But after the first shot.

    the slide will push the hammer back and the trigger will be nice and light only releasing the hammer (SA)

    They will have a "double strike" capability. Because if the hammer falls and the primer does not ignite, pulling the trigger will move the hammer back and release it again.

    Some cheaper models have this like Bersa's

    once you move into glock style triggers in striker fired guns. The term SA is typically thrown around just so you know its a lighter trigger pull. not a long heavy one.
  9. 45Man

    45Man Member

    Easier to explain it with a S&W revolver which does both.

    Double Action - Pulling the trigger cocks & release the hammer.
    Single Action - Cock the hammer with your thumb. Pulling the trigger releases the hammer.

    Colt Peacemaker is single action only revolver as are all the handguns of the old West.

    Beretta 92 is double action on first round, single action on all remaining, unless you de-cock it, then it resets to double action first.

    As usual, Kirk has a more complete explanation.

    BTW, not a stupid question. It was my first question when starting out with handguns.
  10. bluharley

    bluharley Member

    I understand SA/DA when it comes to revolvers, I grew up with revolvers. I just couldn't figure it with a semi-auto, I didn't know they made different cocking mechanisms for those, I thought they all worked basically the same.
  11. GKC

    GKC Lifetime Supporter

    As far as I know, there aren't any revolvers (DA/SA, DAO, or SA) that will cock the hammer under recoil or any other means than either a pull of the trigger or by manual cocking of the hammer. If there is a revolver that self-cocks, please correct me.
  12. cicpup

    cicpup Resident PITA Supporting Member

    Not stupid. Stupid is me taking forever to get them right. Always thought that cocking it and pulling the trigger was me doing two things. Hence DA. Just pulling the trigger is only one action on my part. Therefore SA. Boy did I look like a dumbass when I got schooled on the Bersa forum.
  13. ArmyScout

    ArmyScout Supporting Member

    I have a SA/DA revolver. It's a S&W 38 spl. Problem is the DA trigger pull is a horse. So, I seldom use it. I also have a Bersa 9UC, SA/DA. The DA trigger pull is a pony, not bad at all. All kinds of combo SA/DA triggers out there. Best to check them out before you buy.
  14. Branth

    Branth Member


    Also, there's a somewhat apocryphal story of an old single-action revolver going full-auto when the firing pin hole got so wore out that primers blew out the back of cases, through the hole, and cocked the hammer after each shot, at which time the hammer fell again, set off the next round, blew out the primer, cocked the hammer, etc. until the cylinder was empty.
  15. ajole

    ajole Supporting Member

    NE Utah
    Over 100 years ago...cocked by recoil.

  16. lklawson

    lklawson Staff Member

    An unintended star of The Maltese Falcon, one of my favorite Bogie flicks, and for you trivia buffs, full of lots of hidden homosexual references they managed to sneak past the censors. :)

    Peace favor your sword,
    Last edited: Sep 30, 2014
  17. Kiln

    Kiln Member

    The only stupid question is one that goes unasked and in turn, unanswered.

    We all had to learn this stuff at one point or another so don 't feel too bad. Nobody left the womb with a complete knowledge of firearms...execpt maybe Charlton Heston.
  18. missiledefender

    missiledefender Supporting Member

    Did we muddy the water with DAO yet?

    I say, use what you like and can SAFELY and confidently carry. If you're worried that you'll shoot your C and Bs off with a single action, dont use one. I've been doing it (Cocked and Locked High Power and 1911) for almost 30 years, I still have all of my fingers and toes and my C and Bs.
  19. bluharley

    bluharley Member

    I've learned a lot since that post. I now pocket carry a Kahr CM40 DAO. Still got my B's.
  20. missiledefender

    missiledefender Supporting Member

    I dont sell myself as a expert. It's personal choice. You still have your B' the C still there or did a AD get ya? LOL